Stepping back it is perfectly understandable for Harper and Machado to wait until after the Super Bowl. While things could stretch into training camp, there should be lots of movement the next 2 weeks when baseball starts getting a little more national attention.
At a certain point the Harper and Machado deals are not about bargain shopping. There is a scarcity of stars. The teams should also have an idea of what the market looks like now. Only certain teams can afford these players so there is not much benefit of waiting like there will be for the next tier (i.e. Keuchel, Kimbrel).